Manufacture of adhesive films



Dec. g, 1942. l W, LTY 2,304,263

MANUFACTURE OF ADHESIVE FILMS Filed Sept. 13, 1958 772.2153! Jhee IINVENTOR ATTORNEY Patented 8, 19.42

Fries MANUFACTURE F ADHESIVE Willy Lilty,jEssen-Bredeney, I

by mesne assignments, to The Licor@ tion, New York,

ware

a we 'fr Gorpora- N; Y., a corporation of Dlay Application September 13, 1938, Serial No. 229,799 In Germany September 14, 1937 'i Claims. 'I'his invention relates vto manufacture o'f ref inforced laminated products and adhesive films therefor; and it comprises a method of making tion of heat and pressure, the said metal sheet being advantageously coated by 'passing it through a bath of a heat-setting artificial resin,

(Gi. d-n2) ycombined paper board reinforced adhesive lms adapted to be used in -fthe manufacture of laminated products such as ply-wood, for example, said process comprising' such as a phenol-formaldehyde condensation product, for example, in its initial stage of condensation, the freshly coated metal vsheet'being covered, if desired, on one or both sides' by means of a thin, porous, brous tissue readily penetrated by said artificial resin. The invention also includesv a method of making reinforced laminated products in which the described reinforced adhesive nlm is' inserted between laminations to be united and the assembly is combined by meansof heat and pressure. In addition the invention includes the adhesive films and the laminated products produced by the said processes; all as more Afully hereinafter set.v

forth and as claimed.

Compound lumber, such as ply-wood, combined paper board and other laminated cproducts are commonly made by pasting. one or more of the laminations and then uniting them by means of heat and pressure. In a recent improvement of this method, which is described in the Weber et/al. Patent No. 1,960,176, a sheeted adhesive is employed,` this sheeted adhesive comprising a thin sheet of tissue paper which is impregnated with the alkaline condensation product of phenol @many industrial applications.

special purposes additional strength is greatly desired. There is an important demand for lamand formaldehyde in its initialstage ol condensation and then dried. This sheeted adhesive i's placed between wood plies, for example, the resulting assembly being then subjected to -heat and pressure. The condensation product liqueiles under the action of the heat and forms a hard insoluble'bond between the plies.

Laminated products which are manufactured in the manner` described above are useful in But for many comprises a foramincus, thin metal sheet coated on both sides with a heat-setting adhesive. 'I'he adhesive employed may be any of the usual heat- -setting adhesives which adhere to metal. For

example the adhesive may be made from one of the natural or artificial fusible gums. `But I have found that the initial condensation product of phenol and formaldehyde is particularly suitablefor this purpose. This initial condensation A product is advantageously made as described in the acknowledged patent to'Weberet al. but satisfactory results are obtained by the use'of the so-called Bakelite varnishes which are' on the market and which are usually made by dissolving a phenol-formaldehyde-resin, in various orsanic solvents.

mated products having the finish of ply-wood,

for"e'xampl`e, but'\the strength of metal. The

A present invention l'provides such lted products.

I have found that ply-wood. compound lumber,

The metal sheet employed may be of wire screening, wire gauze or perforatedsheet metal. While various metals can befused, iron and'steel are thecheapest. The metal sheet is coated on both sides, for example by. dipping or spraying, with the heat. setting resin. .It is then dried to the point at which itis hard and non-tacky without being heated to setting temperatures. Heat is usually applied, however, to speed up the drying process by passing a strip through a coating bath of adhesive followed by, drying. If desired sheets of thinv tissue paper may be applied to the metal carrier after the coating operation This prevents the adhesive from collecting in drops on' the carrier and provides a better and more easily handled surface. After the drying operation the adhesive sheet is completed and ready 4to be applied in the manufacture of various laminated products. Y

My invention can be explained tail by reference to the aczompanying drawing which shows, more or less diagrammatically, apparatus elements which can be employed in my continuous method of manufacturing my sheeted adhesive, as well as showing various types of adhesive films and laminated products within the purview of this invention. In. this showing l l I Fig. 1 is an elevational view, partly in section, showing an assembly apparatus elements which may be used in a continuous coating process within my invention, Y v

fFig. 2 is a sectional view on an enlarged scale of a sheeted adhesive made of. wire screen- Fig. 3 is a plan view of a perforated metal sheet coated with adhesive Fig. 4 is a sectional view on an enlarged scaie :through a piece of ply-wood within the present inventiomthis ply-wood being made with the adh esive nlm of Fig. 2, while Fig. 5 isa'sectional view on an enlarged scale through another pieceof ply-wood made of a foraminous metal sheet coated with adhesive and also coated on both sides with a fibrous tissue sheet. Y,

Referring to Fig. l a rollof foraminous metal sheet is shown at i. This, metal sheet is Acontinuously passed through the trough 3 which contains a bath of adhesive 2. The sheet passes around the roller 4 which may be supported in thetrough. .5 and 6 are two rolls-of thin, porous, tissue paper which may. lie-applied bn either or both sides of the coated :metal by the doctor rolls 1. The coated sheet vis then passed between drying units 8 and is finally rolled upon the roll IS; The heaters l are adapted to dry the adhesive. In the case of the use of a phenolformaldehyde resin it is, of course,necessary to` .avoid heating the resin to setting temperatures. If desired the application of the brous tissue to When the reinforced sheeted adhesives of the present invention are employed it is desirable to apply 'sufficient operating pressure to cause the ply-'wood or other fibrous material which'is being pressed to 'enter the perforations in the metal sheet, that is, the metal should become substantially embeddedin .the btolls material.' This produces ran interlocking engagement between the metal and the fibrous material which conis anew result in this art.

yvhi-ie I have described what i eenside'r to be the best embodiments of my invention it isy evident, of course, that-various modincations can `be made in the procedures which have been set l 4out without departing from the purview of this the 'coated metal sheet can be omitted. These paper sheets are so thin and porous that they are readily penetrated by the adhesive and do not ailect the strength of the bond produced. 'I'hey are useful in producing a more uniform distribution ofthe adhesive and also in preventing the checking and chipping of! the fby hand or by machinery after passing the heat' ing units ,l instead of being rolled on the roll I3.'

The laminated articles shown in Figs. 2 to 5 of the drawing are fully described by the use of appropriate legends. The adhesive sheet which is shownin Fig. 2 is made by coating a wire screen with adhesive, while that of Fig. 3 is made from a perforated sheet of metal. If the holes' in the wire screen or in the metal sheet are sufficiently small, these may be `closed byva dried film of adhesive whichjof course, may/be an advantage in that more adhesive is carried by the sheet. The quantity `of adhesive carried by the metal, that is, -the thickness of the adhesive coating on the metal`can bevaried readiLv by control of the temperature and viscosity of the adhesive in the bath. I have found that, for usual applications. only a very thin nlm cf adhesive is required on the metal carrier or reinforcement. The opti-A -mum quantity of adhesive to be employed can be readily determined by test. The 'plywood or other laminated products within the present invention are produced from invention. Forexample, I have found that it is advantageous, with certain types of adhesives which are not satisfactorily adherent to metal, to

mix the adhesive 'with various inert filling ma,- terials, such as wood flour, powdered asbestos, puinice and the like. These fillers appreciably increase the adherence of thevadhesive to the metal. If d sired the adhesive may be applied ,to the carrier indry form, being sprinkled uniformly over the carrier, after which heat or heat and pressure may be applied to spread the adhesive and to cause it to adhere properly to the metal. The heat' appliedin this manner is, of course, merely suillcient to soften the adhesive-without impairment' ofits heat setting properties. If

Adesired the powdered adhesive may be mixed adhesives, the process which comprises coating a foraminous metal sheet with a liquid phenolformaldehyde condensation product capable of.

setting under the'application of heatV and pressure',.the holes in saidmetal sheet being aufliciently small to lie-'closed by a nlm of said conformed covering the entirev metal4 sheet, and

' hardening said nlm to anon-tacky state without impairing its heat setting porperties', thereby prol ducing a reinforced sheeted adhesive which can be having substantially the strength-'ef the weed the sheeted adhesives by the application of heat -an'd pressure by methods well known in the art. Usually the layers of material to be united are assembled with sheetsof adhesive alternating between layers.` This assembly is then inserted stored without becoming 'tacky and used for uniting sheets of ply-wood lupon the application oi' heat and pressure with the production of a bond 2. In the manufacture of reinforced sheeted adhesives', the process which comprises coating a foramincusmetal sheet fwirth a liquid phenolformaldehyde condensation product capable of setting under the application ofl heatand pressure, the holes of said sheet being too large in be closed by a nlm of said condensation product,

applying a thin sheet of porousbrous tissue on at least one side of said metal sheet while said broduct can thenbe remvd 'fr0m n: press. 75 infomed sheetea adhesive which can be stored without becoming tacky and used for unitingV sheets of ply-wood upon the application of heat and pressure with the production of a bond having substantially the strength of the wood itself.

3. A reinforced sheeted adhesive adapted to be employed in the manufacture of compound lumber and other laminated articles, which comprises a foraminous metal carrier sheet, sumciently strong to impart rigidifying characteristics to such a laminated article when incorporated therein, said metal sheet being uniformly coated with an artificial heat-setting resin and in combination with at least one thin sheet of porous fibrous tissue covering at least one face of 'said metal sheet and united therewith by said' resin, said resin being in a hard non-tacky state but being capable of setting to form a permanent bond with wood and other fibrous material upon the application of heat and pressure; the said fibrous tissue sheet being saturated with said resin and serving to hold said resin in the apertures of said foraminous metal sheet, said apertures being too large to sup port a liquid film of said heat-setting resin in the absence of said fibrous tissue sheet.

4. The sheeted adhesive of claim 3 wherein said heat-setting resin is an alkaline condensation product of phenol and formaldehyde in itsinitial stage of condensation.

5. A reinforced sheeted adhesive adapted to be employed in the manufacture of compound lumber and other laminated articles, which comprises a foraminous metal carrier sheet of su'icient strength to impart rigidifying characteristics to such a laminated article when incorporated therein and perforated with apertures sufficiently small to hold and support a lm of an articial heatsetting resin when applied in liquid form to the surface of ,said metal sheet, said metal sheet being coated on both faces, including said apertures, with a continuous film of an artificial heat-setting resin, said resin being in a hard non-tacky state \but being capable of setting to form a permanentr bond with wood and other fibrous material upon the application of heat and pressure, suicient resin being present in said lm to produce a bond between the plies of said laminated article through the apertures of said' metal carrier sheet as well 10 as between said plies and said metal sheet.

6. In the manufacture of reinforced sheeted adhesives, the process whichcomprises applying.

to a foraminous metal sheet a powdered mixture of an artificial heat-setting resin and an inert 1.-, filler capable. of increasing the adherence of said resin to the metal, liquefying said resin by the application of heat, applyinga thin sheet of pov rous fibrous tissue to said metal sheet and uniting said tissue with said metal sheet by means of said gg resin while said resin is suiciently liquid to flow 5 tacky state without impairing its heat-setting properties, thereby producing a reinforced sheeted adhesive which can be stored without becoming tacky and used for uniting sheets of compound lumber upon the application of heat and pressure 5;) with the production of a bond having substantially the strength of the wood itself, said metal sheet being suiicientlylstrong to impart rigidifying characteristics to said compound lumber.

'7. The sheeted adhesive of claim 5 wherein said 3:, heat-setting resinA is an alkaline condensation product of phenol and formaldehyde in its initial stage of condensation.-

WILLY LUTY'. 

